基于甲基纤维素改性聚乙烯醇指示膜的制备、表征及对南美白对虾的鲜度指示

为实现水产品鲜度可视化实时监测,本研究以甲基纤维素（methyl cellulose,MC）共混改性聚乙烯醇（polyvinyl alcohol,PVA）为成膜基材,复配溴甲酚紫甲基红制备指示膜,比较基材配比对结构、物理及检测性能的影响,并应用于南美白对虾鲜度检测。结果表明：各组分相容性强,流变学结果表明m（MC）∶m（PVA）＝3∶1时分子间作用力最强烈。MC的引入可改善PVA性能,当PVA和MC质量比为1∶3时,指示膜具有最高的抗拉强度（（65.36±4.29）MPa）、疏水性能（水接触角（57.30±0.81）°）和阻隔性能。各指示膜均能对pH值响应,且具良好颜色稳定性。将性能最优的指示膜用于南美白对虾（4 ℃）鲜度检测,4 d时指示膜由红褐色转为紫褐色,对应次级鲜度;8 d时pH值和总挥发性盐基氮（total volatile basic nitrogen,TVB-N）含量分别达7.73±0.01和（60.90±7.00）mg/100 g,指示膜变为黑色,对应完全腐败。差异显著性分析表明指示膜颜色在不同鲜度区间具有明显差异,相关性分析表明指示膜色差值与pH值、TVB-N含量呈显著（P＜0.05）或极显著（P＜0.01）相关。鉴于伴随虾不同程度的腐败,指示膜可产生肉眼可辨的颜色变化,故可根据指示膜颜色对所保鲜虾类的鲜度等级进行划分,实现食品鲜度实时监控,具良好应用前景。     

Development of a pH indicator composed of high moisture-absorbing materials for real-time monitoring of chicken breast freshness

A colorimetric bromocresol purple dye-based pH-responsive indicator was developed to monitor the quality of chicken breast meat by direct surface contact. To prevent direct contact of the dye with the chicken breast and to improve its color change sensitivity, it was immobilized with polyvinyl alcohol and a high-absorbance material. The color of the pH indicator changes from yellow to blue and finally purple to indicate spoilage, which can be easily detected by the naked eye. The asprepared pH indicator exhibited good response to pH changes on the surface of chicken breast meat, and no migration of the dye from the indicator onto the surface of the chicken was observed. This pH indicator exhibits excellent feasibility for real-time, direct-contact monitoring of the freshness and quality of various foods.     

结冷胶-沙蒿胶-蓝莓花青素可食性膜的制备及其性能分析

利用蓝莓花青素对pH值的指示作用制备智能包装膜,以期解决食品保鲜过程中新鲜度的检测难题。以结冷胶、沙蒿胶和蓝莓花青素为主要原料,采用流延法制备智能指示膜,研究膜的色差、机械性能、水溶性、水蒸气透过率以及微观结构等分析其性能。结果表明,红外扫描和电镜分析表明沙蒿胶与结冷胶及蓝莓花青素之间具有良好的相容性;沙蒿胶能够提高结冷胶/沙蒿胶-蓝莓花青素膜的厚度、膜的断裂延伸率、水蒸气透过率,降低膜的抗拉伸强度和水溶性;结冷胶/沙蒿胶复配比8∶2(质量比)时,花青素膜的断裂延伸率最大为47.36%,水蒸气透过率为7.643×10^-6 g·m/(d·Pa·m^2),抗拉强度22.08 MPa,复配比4∶6(质量比)的膜厚度达到0.079 mm;复合膜对pH值的指示作用显著,可作为pH指示膜。本研究为新型食品保鲜智能指示膜的应用提供理论基础。     

用于食品质量监测的pH智能指示剂的研究进展

近年来,消费者对于食品安全要求的改变促进了包装新技术的发展。目前用于食品质量监测的智能包装技术主要有指示剂、数据载体装置以及传感器等。其中,pH智能指示剂由于其成本低、体积小、制备方便和指示效果好等优点而成为研究热点。通常来说,指示剂是由负载基和pH染料组成。同时天然pH染料如茜素、姜黄素、类胡罗卜素、花青素等对于环境酸碱性的改变能表现出明显的颜色变化。以天然pH染料制备的pH智能指示剂能够传递食品的实时信号（颜色、化学或电子）,以表现实时的质量信息。本文主要对以天然染料和生物聚合物为基础的pH智能指示剂的研究现状进行了概述,讨论了基于天然pH染料和合成pH染料相比的pH智能指示剂的重要性,以及未来的研究趋势。     

Dual bacterial strains TTI for monitoring fish quality in food cold chain

Most microbial time–temperature indicators (TTIs) considered only one spoilage strain. This research compared single and dual spoilage strains-based microbial TTI for quality changes of chilled grouper fish (Epinephelus fuscoguttatus x E. lanceolatus) fillet products during distribution. The next-generation sequencing (NGS) and traditional plate count approach showed that Pseudomonas fragi and Vibrio parahaemolyticus were specific spoilage bacteria at 7 and 15°C. A dual-strain TTI response provides more accurate results than a single-strain TTI and provides an irreversible color change from yellow to reddish-brown, showing levels of fish freshness. The microbial TTI comprises fish spoilage bacteria strains with 3 log CFU/ml, a nutrient broth supplemented with 2% NaCl as a medium, and phenol red with 0.25 mg/ml as a pH indicator. Overall, this study points to the applicability of a dual-strain microbial TTI as a valuable tool for monitoring fish quality changes during cold chain break condition.     

Chitosan biobased and intelligent films: Monitoring pH variations

Many factors can influence the shelf-life product, such as pH, water activity, nutrient levels available oxygen, etc. Variations in food pH could occur due to microorganism growth and chemical reactions that may impact flavour, consistency and shelf-life. The objective of this paper was to obtain and characterize the fast pH-colourimetric indicator device, applying a simple manufacturing technique, using food grade and biodegradable materials. The intelligent film was based on natural compounds as chitosan and anthocyanin (pH-colourimetric indicator). Chitosan intelligent films (C-ATH, 2.0 g/100 g) were obtained incorporating anthocyanin (1.0 g/100 g) in matrix films. Initially, a dark violet colour was observed in chitosan films dried. When immersed in different pH buffers, the colour range of the films varied from pink (in acid pH) to bluish-green (in neutral pH) and to violet (in basic pH). The water solubility and water vapour transmission rate of C-ATH were decreased to 60% and 48%, respectively, as compared to control film (CF, without indicator). The mechanical properties such as tensile strength and rigidity were maintained, and the elongation at break was reduced to 47% compared to CF. The advantages of this system were the simple manufacturing process, biodegradability and usage of natural and safe compounds.     

花青素与姜黄素在食品包装领域的应用

花青素和姜黄素对于活性包装至关重要,探讨其内在机理,可为花青素、姜黄素智能包装膜的相关研究提供理论参考。本文综述了花青素、姜黄素的结构和性质、提取方法、抗氧化活性、花青素和姜黄素在食品包装上的应用以及两种色素混合在食品包装上的应用。花青素和姜黄素由于其自身结构特点,在不同的pH下有不同的颜色,花青素作为颜色指示剂变色范围广,但性质不稳定,易受到外界因素影响。姜黄素稳定性高于花青素,但变色范围窄。此外,两者均具有很好的抗氧化活性,可作为颜色指示剂与抗氧化剂应用在食品包装中。花青素和姜黄素的变色特点、稳定性以及功能活性对食品新鲜度指示包装的性能具有显著的影响,将两种色素混合作为指示剂添加到食品包装中,有助于提高花青素的稳定性,从而获得更好的指示效果。     

Evaluation of a freshness indicator for quality of fish products during storage

A freshness indicator consisting of a polymer matrix solution containing the pH-sensitive dye bromocresol green was investigated for monitoring visible color changes of fish spoilage volatile compounds based on the quantity of volatile amines. Mackerel fillets were inoculated with Pseudomonas fragi and stored in incubators at 5, 12, 18, and 25°C. Chromaticity values of the freshness indicator accurately tracked an increase in the trimethylamine content in the packaging headspace. Gradual color changes of the freshness indicator response correlated with the quality of fish, including growth of P. fragi and pH values during storage. Results will be useful to establish a basis for development of a freshness indicator and to determine the suitability of freshness indicator formulations for intelligent food packaging applications.     

Active/smart carboxymethyl cellulose-polyvinyl alcohol composite films containing rose petal extract for fish packaging

In this study, a film was developed for packaging fish that not only enhanced its shelf life but also was visually receptive to its spoilage. Rose petal extract (RPE) having excellent bioactivity was used as the functional component in carboxymethyl cellulose-poly vinyl alcohol packaging film. Due to its high anthocyanin content, RPE could be used as a pH indicator, as its colour changed from bright red (pH 2) to yellow (pH 10). The developed film was used for packing Indian Mackerel and assessing its quality during chilled storage. Mackerel packed in neat film spoiled in 3 days while that in RPE containing films had shelf life of 12 days. Total bacterial count, pH, total volatile basic nitrogen and thiobarbituric acid reactive substance of fish in control were higher as compared to in RPE films. On spoilage RPE containing films showed visible colour response from red to green.     

基于酰基化花青素的高稳定性新鲜度可视化指示膜及其应用

本研究将提取的玫瑰茄花青素酰基化,比较分析了酰基化前后花青素在不同温度和光照条件下的稳定性,结果表明酰基化花青素具有较高的光热稳定性。以聚乙烯醇和β-环糊精作为成膜基材,花青素作为指示剂,制备智能指示膜并研究其机械性能、灵敏度和颜色稳定性等。结果显示：酰基化玫瑰茄花青素/聚乙烯醇/β-环糊精(polyvinyl alcohol/β-cyclodextrin/acylated roselle anthocyanin,PCRA)膜的拉伸强度约为玫瑰茄花青素/聚乙烯醇/环糊精(polyvinyl alcohol/β-cyclodextrin/roselle anthocyanin,PCR)膜的3倍,且PCRA膜的微观结构致密,水蒸气透过率较高,为2.06×10^-6 g/(m·h·Pa);同时指示膜表现了较高的稳定性但其灵敏度下降。最后将PCRA膜用于典型高价值牛肉新鲜度的监测,结果表明,在4℃贮藏环境下,牛肉在第6天时的挥发性盐基氮含量为16.81 mg/100 g,表明牛肉已经不新鲜,此时PCRA膜的颜色由粉色变为蓝绿色,可有效反映牛肉的新鲜度;同时将牛肉品质的理化信...     

Real-Time Monitoring of Shrimp Spoilage Using On-Package Sticker Sensor Based on Natural Dye of Curcumin

The development of a curcumin-based sensor for the detection of volatile amines (specifically known as total volatile basic nitrogen, TVBN) is described. Curcumin [(1E,6E)-1,7-bis(4-hydroxy-3-methoxyphenyl)hepta-1,6-diene-3,5dione] is the major yellow pigment extracted from turmeric, a commonly used spice, derived from the rhizome of the plant Curcuma longa. Curcumin was immobilized onto bacterial cellulose membrane via the absorption method. Thus, the sensing materials are edible and suitable for food applications. The curcumin/bacterial cellulose membrane as the TVBN sensor worked based on pH increase as the basic spoilage volatile amines produced gradually in the package headspace, and subsequently, the color of the sensor will change from yellow to orange, then to reddish orange for spoilage indication, which is easily visible to the naked eye. The curcumin membrane is a highly sensitive material toward acid–base reactions. Color changes, as a result of its interactions with increasing pH (as a result of increasing TVBN), were monitored directly with visual inspection and the color quantitatively measured with color analysis via Photoshop software. Furthermore, the membrane response was found to correlate with bacterial growth patterns in shrimp samples. Finally, the curcumin/bacterial cellulose membrane was successfully used as a sticker sensor for real-time monitoring of shrimp spoilage in ambient and chiller conditions.     

Influence of alkalization treatment on the color quality and the total phenolic and anthocyanin contents in cocoa powder

The effects of alkalization treatments on color, colorimetric fractions, total polyphenol content, and anthocyanin content of cocoa powder were investigated. A darker color and a lower total polyphenol content were obtained for cocoa powder alkalized using a K₂CO₃ solution than with an NaOH solution. A high temperature and basic pH conditions favored formation of dark components during alkalization due to sugar degradation, Maillard reactions, and anthocyanin polymerizing. The anthocyanin content decreased with an increasing alkali concentration, suggesting that more anthocyanins were transformed into brown polymers in darker cocoa powder. Cocoa powder with a heavy degree of alkalization had the lowest ratio of monomer anthocyanins to yellow/brown polymer content. OD₄₆₀/OD₅₂₅ values for alkalized samples were higher than for non-alkalized samples. Cocoa powder presented a better color quality after alkalization treatment.     

Monitoring the biogenic amines in Chinese traditional salted pork in jelly (Yao‐meat) by colorimetric sensor array based on nine natural pigments

To develop simple, cheap and convenient sensors for Yao‐meat freshness evaluation and biogenic amines (BAs) detection, a colorimetric sensor array was made by printing nine natural pigments on a hydrophobic nanoporous film. A colour change profile for each sample was obtained by differentiating the image of sensor array before and after exposure to volatile organic compounds (VOCs). The sensor array was exposed to atmospheres containing BAs vapours with concentrations over the range 10–30 ppm. Rosa chinensis extract possessed the highest sensitivity thanked to the highest anthocyanin contents. The results of principal component analysis (PCA) showed that the measurements corresponded to three freshness levels were separated clearly. The partial least‐squares prediction model was obtained with the correlation coefficients of 0.921 and 0.907 in calibration and validation sets, respectively. This research suggested that the anthocyanins content pigments maybe a very useful colorimetric sensor for quality evaluation of meat.     

pH敏感性材料在智能食品包装中的应用进展

随着消费者食品安全意识的增强,通过包装颜色变化对食品品质进行直观判断成为一个新的需求,智能包装近年来成为学界和产业界的共同关注点。pH敏感性材料与聚合物混合后获得的食品包装膜,在不同的pH条件下显示不同颜色,具有实时监测肉、虾、牛奶等食品新鲜程度的效果。本文介绍了化学显色剂和天然色素显色剂两大pH敏感性型指示器,分类介绍花青素、姜黄素、茜素、紫草素、甜菜碱等天然食品色素在不同pH下的变色机理,总结了pH敏感性材料与不同聚合物共混改性后在食品包装领域的研究进展、应用现状和研究趋势,为制备性能良好、绿色环保的智能食品包装提供参考。     

A halochromic indicator based on polylactic acid and anthocyanins for visual freshness monitoring of minced meat,chicken fillet,shrimp, and fish roe

Herein, a new intelligent indicator with polylactic acid (PLA)/ polyethylene glycol (PEG)/calcium bentonite (CB) blend and Malva sylvestris, as a source of anthocyanins, was developed, characterized, and used for visual freshness monitoring of a variety of proteinous foods. Anthocyanins were incorporated successfully into PLA/PEG/CB with no significant change in the chemical structure of the indicator. The hydrophilic (water contact angle of 43.9°) indicator represented visual color changes from light red (at pH 2) to green (at pH 11). Moreover, PLA/PEG/CB-Malva indicator visually distinguished (ΔE > 5) fresh, medium fresh, and spoiled shrimp and fish roe (during 6 days at 4 °C), but discriminated only fresh and spoiled minced beef and chicken fillets (during 10 days at 4 °C), which were strongly correlated with the total volatile basic nitrogen of food samples. The PLA/PEG/CB-Malva indicator has a satisfying application for monitoring the freshness of various proteinous foods.Industrial relevance textThis study showed that anthocyanins extracted from Malva Sylvestris can be used efficiently in food smart packaging. The incorporation of anthocyanins into polylactic acid has led to the production of a novel intelligent freshness indicator. The indicator revealed an appropriate response to the spoilage of different proteinous foods with the capacity to differentiate between fresh, medium fresh, and spoiled foods. This capability is an important feature in commercializing freshness indicators.     

PVA/starch/propolis/anthocyanins rosemary extract composite films as active and intelligent food packaging materials

Active and intelligent food packaging films has taken more importance over conventional packaging. The aim of this study was to develop active and intelligent food packaging films based on bio-degradable polymers like polyvinyl alcohol and starch, incorporated with natural additives, that is, propolis extract (PE) and Anthocyanin. Boric acid was used as a cross-linker. The results proved the compatibility of films mixture. The mechanical strength was also measured and highest value was achieved 6.1 MPa for films containing 20% PE. Moreover, the maximum zone of inhabitation, that is, 21 and 15 mm, was also achieved at same composition against Escherichia coli and methicillin-resistant Staphylococcus aureus, respectively. Furthermore, all films had shown great color response against different pH ranging from 2 to 14. Finally, food spoilage test was performed using pasteurized milk. Films responded visibly by changing color and protected milk from spoilage. Hence, formulated bio-degradable active and intelligent films can be used as food packaging material.     

Quantification of anthocyanins in black carrot extracts (<Emphasis Type="Italic">Daucus carota</Emphasis> ssp.<Emphasis Type="Italic"> sativus</Emphasis> var.<Emphasis Type="Italic"> atrorubens</Emphasis> Alef.) and evaluation of their color properties

Pigment composition of 15 black carrot cultivars (Daucus carota ssp. sativus var. atrorubens Alef.) was screened by HPLC-MS. Up to seven cyanidin glycosides, five of which were acylated with hydroxycinnamic and hydroxybenzoic acids, were identified and quantified in the roots by HPLC-DAD. Contents of individual compounds indicated great differences in the potential of anthocyanin accumulation both between different cultivars and carrots of the same cultivar. Total anthocyanin amounts ranged from 45.4 mg/kg dry matter to 17.4 g/kg dry matter. To the best of our knowledge, this is the first report on the quantification of individual anthocyanins in roots of different black carrot cultivars. The determination of color properties in the extracts under various pH conditions proved black carrot anthocyanins to be applicable as natural food colorants also for low-acid food commodities, whereas a considerable loss of color was noted under nearly neutral conditions. Additionally, relatively high saccharide contents were found in almost all cultivars which may be disadvantageous when coloring concentrates are produced from carrot roots.     

卡拉胶基复合花青素微胶囊指示膜的制备、表征及其对冷鲜牛肉新鲜度的监测

为了研制一种稳定的花青素指示膜用以监测冷鲜牛肉的新鲜度,本研究先制备出复合花青素微胶囊（composite anthocyanin microcapsules,CAM）,再以卡拉胶（carrageenan,Car）和羧甲基纤维素钠（carboxymethyl cellulose,CMC）为膜基材,加入不同体积分数（5%、10%、15%、20%）的CAM制备Car/CMC/CAM（CC/CAM）指示膜,并对不同膜的结构和物理性能进行表征,然后将指示膜应用于牛肉新鲜度的监测中。结果表明,CMC的加入提升了单一Car膜的机械性能、阻隔性能和热稳定性;其中指示膜CC/CAM-3的抗拉伸强度（17.76 MPa）最高,水蒸气透过率（1.35×10－11 g/（m·s·Pa））最低,横截面紧实整齐;傅里叶变换红外光谱分析结果表明指示膜的各组分结构相似,相容性良好。指示膜暴露于氨气中,膜颜色发生显著变化,由最初的粉色逐渐变成蓝绿色,最终变为黄色,利用这一特性对4 ℃贮藏条件下牛肉新鲜度进行监测,结果表明牛肉在贮藏第4天和第7天分别达到次级新鲜和腐败,相应地指示膜CC/CAM-3也从粉色变为紫色和绿色。综上,CC/CAM-3对牛肉新鲜度变化最敏感,可用于监测其新鲜度。     

Effects of specific egg yolk antibody (IgY) on the quality and shelf life of refrigerated Paralichthys olivaceus

BACKGROUND: The spoilage of fishery food has been attributed to limited types of microorganisms called specific spoilage organisms (SSO). Unlike traditional food‐preserving techniques which usually exploit broad‐spectrum antimicrobial agents, here, based on the specific antimicrobial activity of egg yolk antibodies (IgY) against two SSO in refrigerated fish (Shewanella putrefaciens and Pseudomonas fluorescens), a novel strategy for fish preservation was suggested and evaluated. RESULTS: During storage of Paralichthys olivaceus fillets at 4 ± 1 °C, the bacteria growth (including total microorganisms and the two SSO) in test groups was significantly inhibited in comparison to that of controls (P < 0.05). This antibacterial activity of the specific IgY was also confirmed by chemical analysis (pH, total volatile base nitrogen and 2‐thiobarbituric acid value) and sensory evaluation, and the shelf life of samples was extended approximately from 9 days to 12–15 days in the presence of the specific IgY. CONCLUSION: These results indicated a significant antimicrobial activity of the anti‐SSO IgY for refrigerated fish products, which allowed us to suggest its potential as a bio‐preservative for seafood. Copyright © 2011 Society of Chemical Industry     

基于纳米材料的比色传感策略检测沙门氏菌的应用进展

沙门氏菌是常见的食源性致病菌, 具有致病性强、分布广泛等特点, 其造成的食品污染危害已成为世界性的公共安全卫生问题。纳米材料种类繁多, 其比表面积大、吸附能力强、活性位点多,比色传感策略因其简单、便携、低成本和可视化也被广泛用于食品安全检测。将纳米材料与比色传感策略相结合, 为检测沙门氏菌提供了新的思路,已成为食品安全检测领域研究热点。本文综述了近些年国内外基于纳米材料结合比色传感策略快速检测沙门氏菌的研究进展, 重点阐述了纳米酶催化底物显色、部分贵金属纳米材料表观颜色变化和纳米材料与pH指示剂结合, pH变化诱导颜色变化, 以检测沙门氏菌的比色传感策略的原理及应用, 并对该领域未来发展前景进行了展望, 以期为今后开发简单、便捷、高效的沙门氏菌的比色检测方法提供参考。